Use Tempest-lib's compute security_group_default_rule

Compute security_group_default_rule has been migrated to
tempest-lib- I8b652aeb82d2a7335212ef7cc021a969ad297c6a

Now Tempest-lib provides this client as stable interface so Tempest
should start using this from lib and remove its own copy.
Also remove its unit tests.

This commit makes Tempest to use compute security_group_default_rule
from Tempest-lib.

Change-Id: I6be919a2845a08426758d19890919e6d97d2161d
diff --git a/tempest/clients.py b/tempest/clients.py
index 393be71..29f154c 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -45,6 +45,8 @@
 from tempest_lib.services.compute.quota_classes_client import \
     QuotaClassesClient
 from tempest_lib.services.compute.quotas_client import QuotasClient
+from tempest_lib.services.compute.security_group_default_rules_client import \
+    SecurityGroupDefaultRulesClient
 from tempest_lib.services.identity.v2.token_client import TokenClient
 from tempest_lib.services.identity.v3.token_client import V3TokenClient
 
@@ -60,8 +62,6 @@
 from tempest.services.compute.json.interfaces_client import \
     InterfacesClient
 from tempest.services.compute.json.keypairs_client import KeyPairsClient
-from tempest.services.compute.json.security_group_default_rules_client import \
-    SecurityGroupDefaultRulesClient
 from tempest.services.compute.json.security_group_rules_client import \
     SecurityGroupRulesClient
 from tempest.services.compute.json.security_groups_client import \